The use of masonry blocks in the construction industry has been widespread for many years. Masonry blocks are constructed of various materials, lightweight concrete being the most prevalent. Various designs of blocks have also been utilized, many attempting to minimize the weight of the block while preserving as much structural strength as possible. Common block designs incorporate exterior walls connected by webs of various designs, creating interior cores of air space. In addition to reducing the weight of the block, the air space provides for decreasing the overall thermal conductivity of the block. Insulation inserts are also used in the cores to further decrease the thermal conductivity of the blocks.
Historically, most masonry block wall construction has consisted of staggered block construction with mortar joints between blocks of each course and between successive courses of blocks. The mortar joints provide for leveling and maintaining uniform dimensions for each course of block despite variations in the dimensions of individual blocks.
Dry stack block construction, masonry block construction without the use of mortar between adjacent block, has not achieved widespread use to date. However, some of the principal advantages of dry stack block, in comparison to mortared block construction, are the increased speed of construction and the decreased labor costs. A lesser skill level is required for workmen that merely stack block along a desired wall alignment. Further, hod tenders are not needed. As with a common mortared block wall, the primary structural strength of the dry stack wall is derived from the horizontal bond beams and vertical grout columns, each with one or more reinforcing bars (“rebar”) grouted in place.
U.S. Pat. No. 4,748,782 (Johnson '782) and U.S. Pat. No. 4,769,964 (Johnson '964) to Johnson disclose a dry stack block and methods for using a dry stack block to construct a wall. The present inventors' experience with the block of Johnson '964 and Johnson '782 has led them to conclude that the block is neither self-aligning nor self-leveling. The inherent difficulty in manufacturing the dry stack block and the cell cores disclosed by Johnson '964 and Johnson '782 to precise dimensions, the variability, albeit lesser, in the dimensions of the cell cores, and the compressibility of the cell cores, albeit slight but variable depending on the density of the cell core, of the cell cores, provides for inadequate and inconsistent alignment and leveling of the block courses. Further the intended extension under Johnson '964 and Johnson '782 of the top of the cell core above the top of each block and each block course, purportedly to provide for horizontal alignment of the block of each course and for uniform vertical spacing between the block of adjacent courses, has been found by the present inventors to be ineffective. The experience of the present inventors has further led them to conclude that the transfer of vertical load from one course to another, during construction or thereafter, through the cell cores, is undesirable. The foregoing limitations of the block, the block wall, and the method of Johnson '964 and Johnson '782 appear to be due primarily to lack of dimensional uniformity of the block, and variations in the dimensions and density of the cell cores.
Another particular problem noted with the dry stack block of Johnson '964 and Johnson '782 is that crumbing inherently occurs in the block manufacturing process causing crumbing to be deposited in and cemented in the notch bottom (“crotch”) of web notches in the block intended to receive the ears of the insulating, aligning, and leveling cell cores. This causes the ears of the cell cores to fit poorly in the corresponding block web notches, further inhibiting the intended aligning and leveling function of the cell cores.
It is an object of the present invention to provide a dry stack block cell core and dry stack block assembly that are practical to use for the construction of a block wall, reduce the required skill and cost of labor used to construct the wall, and provide for the construction of a block wall with enhanced thermal resistivity and good structural characteristics.
It is a further object of the present invention to provide a method for constructing a dry stack block wall for which the required skill and cost of labor used to construct the wall is reduced, and the thermal resistivity is enhanced.
It is a further object of the present invention to provide a dry stack block cell core, dry stack block assembly, dry stack block wall, and method for constructing a dry stack block which will address some of the deficiencies of the dry stack block of Johnson '964 and Johnson '782, and in particular with the cell core.
It is a further object of the present invention to provide a dry stack block cell core and dry stack block assembly which will improve the ability of the cell core to accommodate crumbing in the notch bottom of the block web notches.
It is a further object of the present invention to provide a dry stack block cell core and dry stack block assembly which will improve the ability of the cell core to accommodate variations in the dimensions of the dry stack block.
It is a further object of the present invention to provide a dry stack block cell core and dry stack block assembly which will improve the ability of the cell core to accommodate variations in the dimensions and density of the cell core.
It is a further object of the present invention to provide a dry stack block cell core, dry stack block assembly, dry stack block wall, and method for constructing a dry stack block which will provide for reducing and ameliorating the alignment and leveling problems of the block, the wall, and the method of Johnson '964 and Johnson '782.
It is a further object of the present invention to provide a dry stack block cell core, dry stack block assembly, dry stack block wall, and method for constructing a dry stack block wall providing for an improvement in the manner and method of accommodating rebar for the horizontal bond beams and the vertical grout columns.